Introduction to the Human Cardiovascular System

Introduction to the Human Cardiovascular System

• The cardiovascular system is the body's transport system.
• It is composed of blood, heart, and blood vessels.
• The cardiovascular system delivers nutrients and removes waste products from tissues.
• Blood, the conveying medium, flows through a closed tubular system.
• The system includes the heart and blood vessels.
• The heart is a four-chambered, hollow muscular organ roughly the size of a fist.
• The heart is located superior to the diaphragm, to the left of the midline, and anterior to the vertebral column, and posterior to the sternum.

Functions of the Cardiovascular System

• Transports nutrients and hormones.
• Removes waste products.
• Facilitates gaseous exchange.
• Plays a role in immunity.
• Blood vessels carry blood, oxygen, carbon dioxide, nutrients, and waste products.
• The heart pumps blood through the blood vessels.

Components of the Cardiovascular System

• Blood (blood cells & plasma).
  • Erythrocytes (red blood cells)
  • Leukocytes (white blood cells)
  • Thrombocytes (platelets)
  • Plasma (fluid portion).
• Heart.
• Blood vessels.

Blood Vessels

• A closed network of tubes.
  • Arteries (distributing channel)
    • Thick-walled tubes.
    • Elastic fibers.
    • Circular smooth muscle.
  • Capillaries (microscopic vessels)
    • One cell thick.
    • Exchange of nutrients and gases occurs here.
    • Continuous capillaries are present in skin, lung, smooth muscle, etc. Fenestrated capillaries are found in the pancreas, endocrine glands, small intestine, choroid plexus, and ciliary processes. Sinusoids are large, irregular vascular spaces found in the liver, spleen, bone marrow, suprarenal, and parathyroid glands.
  • Veins (draining channel)
    • Thin-walled.
    • Large, irregular lumen.
    • Have valves.

Arteries

• Carry oxygenated blood away from the heart.
• Thickest blood vessels.
• Accompanied by veins and nerves.
• Lumen is small.
• No valves.
• Repeated branching.
  • Elastic arteries (e.g., aorta and its major branches).
  • Muscular arteries (e.g., renal, testicular, radial, tibial arteries).
  • Arterioles (diameter < 0.1 mm)
    • Terminal arterioles.

Veins

• Carry deoxygenated blood back to the heart.
• Thin-walled.
• Have valves that prevent backflow.
• The factors responsible for venous return are muscle contraction, negative intrathoracic pressure, pulsation of arteries, gravity, and valves.

Circulation

• Coronary circulation: blood flow within the heart.
• Pulmonary circulation: blood flow between the heart and lungs.
• Systemic circulation: blood flow between the heart and body cells.
• Fetal circulation (specific to a fetus)

Portal Circulation

• Blood flow between two sets of capillaries before draining into a systemic vein.
• This is important for specific organs like the liver.

Classification of Arteries

• Elastic arteries (Aorta & its Major branches)
• Muscular arteries (Renal, Testicular, Radial, Tibial etc).
• Arterioles ( > 0.1 mm)

Anastomosis

• Communication between vessels.
• End arteries do not communicate with adjacent arteries.
• Collaterals are accompanying extra arteries to an area.
• Arteriovenous anastomoses are found in certain body areas.

End Arteries

• Central artery to the retina.
• Arteries of spleen, liver, kidneys, long bone metaphyses.
• Central branches of the cerebral cortex.

Capillaries (5-8 micrometres)

• Smallest blood vessels, connect arteries and veins.
• Site of nutrient and gas exchange.

This quiz explores the components and functions of the human cardiovascular system. It covers the roles of blood, the heart, and blood vessels in transporting nutrients and waste throughout the body. Understand how this critical system supports overall health and facilitates essential processes.